This invention relates to lubricating systems generally and relates more particularly to an injector for accurately controlling the amount of lubricant being injected.
Rotating and sliding parts of mechanical equipment require lubrication to keep friction produced wear to a minimum. As equipment becomes more complex and the number of lubrication points increases, manual lubrication procedures become inefficient and are often unreliable in that maintenance time and costs rise, there is little control over the quantity of lubricant dispensed and the likelihood of overlooking lube points increases. To overcome these problems, the prior art has provided an economical solution in the form of centralized lubrication systems. The centralized system guarantees that each lubrication point receives a quantity of lubricant on an automatic cyclic basis, thereby freeing maintenance personnel for other tasks.
A typical centralized lubrication system includes a reservoir to store lubricant, a pump to deliver lubricant, a device to activate the pump, an injector to dispense a quantity of lubricant to a lube point, and associated tubings and fittings to connect components. In systems of this type the injector is the key to achieving reliable operation. Among injectors common to the prior art are (1) dynamic injectors, (2) metering dispensers and (3) positive displacement injectors utilizing either ball check valves or U-cup seals.
Dynamic injectors require high pressure surges to dispense lubricant around balls contained in a closely fitting hole. High pressure demands of dynamic injectors require the lubrication system to have high pressure pumps, heavy lines, heavy fittings, and other high cost elements. As will hereinafter be seen, lubrication systems constructed in accordance with the instant invention utilize a novel positive displacement injector that operates at relatively low pressures so that the system uses low cost pumps, lines and fittings, resulting in lower system cost.
Metering dispensing devices rely on small orifice openings to restrict lubricant flow. The quantity of lubricant dispersed is not positive, being effected by pump pressure and cycle time. The small orifice openings make these devices sensitive to lubricant contaminants. In contrast, the positive displacement injector of this invention is not sensitive to pump pressure or cycle time, and in a positive manner delivers a premeasured quantity of lubricant each cycle. Small orifice openings are not utilized by the positive displacement injector of this invention so that it is not unduly sensitive to lubricant contaminants.
Prior art positive displacement injectors commonly employ ball check valves and U-cup seals to seal and to control flow direction. These types of injectors are bulkier and more sensitive to contaminants than the injector of this invention. The latter utilizes relatively low cost rugged elements that are readily assembled, while the ball check valve-type requires costly elements having fine finishes and the U-cup seal-type requires special procedures for assembling fragile elements.
Accordingly, the primary object of the instant invention is to provide a novel reliable positive displacement injector that is particularly useful for a centralized lubrication system.
Another object is to provide a positive displacement injector that is of simple, low-cost construction.
Still another object is to provide a positive displacement injector that is rugged and compact.
A further object is to provide a positive displacement injector which utilizes a novel disk-seal to provide low cost face seals on two surfaces and also functions as a check valve.
A still further object is to provide a novel positive displacement filter that utilizes a piston assembly to dispense lubricant and to refill the injector.
These objects as well as other objects of this invention shall become readily apparent after reading the following description of the accompanying drawings.